How 'The Simpsons' Works

Bart's chalkboard sequences are one of many memorable gags on "The Simpsons." FOX via Getty Images

This list is where Simpsons fans all nod and smile, while non-Simpsons fans make that "I'm not sure if this milk is still good" face (then drink it anyway):

The blackboard gag (aka chalkboard gag): The title sequence of many episodes is altered to show Bart writing a different message on the school blackboard, presumably as part of his detention.

The couch gag: The title sequence features the entire Simpson family entering the living room and sitting on the couch, but is altered in each episode to show a variety of mishaps and misadventures. Usually, something bad happens to Homer.

The Treehouse of Horror: Every fall a trio of spooky tales spoofing various horror and sci-fi movies lets the writers and animators throw away continuity and kill off the main characters in hilariously disturbing ways.

Guest stars: There have been hundreds of guest stars on "The Simpsons." Popular Irish rock band U2 was one of them. Several U.S. presidents were, too, although none have voiced themselves. Former British Prime Minister Tony Blair played himself, though.

The theme song: It's so catchy! It was composed by Danny Elfman, who was in an '80s band called Oingo Boingo and is best known for scoring multiple movies by director Tim Burton.

"The Simpsons" did it already: There have been so many Simpsons episodes covering such a massive swath of American pop culture and satirical topics that virtually any story idea or gag seemingly has been done on the show. Other shows have done entire episodes making fun of the fact that "The Simpsons" has done everything.

Catchphrases: D'oh! Hey hey! Ay, ay, ay! No es bueno! Eeeeeeexcellent. Worst. Episode. Ever. Meh. Characters on "The Simpsons" are known for catchy catchphrases. And if you're thinking of making an ironic comment about how "The Simpsons" uses lots of catchphrases, "The Simpsons" did it already.

Predicting the future: There are some weird coincidences that, in retrospect, make it seem like "The Simpsons" was eerily accurate at predicting future events. But there's something of a Nostradamus effect happening — it's easy to interpret a wacky element of a Simpsons episode in a way that makes it fit a real-world event. "The Simpsons" also did not predict Donald Trump running for U.S. president. A clip showing him announcing his candidacy was created after the actual announcement, although it's often associated with an incorrect airdate. "The Simpsons" did make a joke back in 2000 about a future Trump presidency bankrupting the country, and Bart's blackboard gag saying "'the president did it' is not an excuse" in 1998 was a reference to Bill Clinton, as much as it may seem to fit current events.

In the next section, we'll take a look at the vast cultural impact of "The Simpsons," and give all our readers free doughnuts.